This paper proposes a novel discontinuous pulse-width modulation (DPWM) method to reduce the current harmonics and improve
the system efficiency for a single-phase three-level neutral-point clamped inverter. In single-phase inverters, the unipolar pulse-width
modulation (UP-PWM) method is commonly used. However, this method has the disadvantage of power losses due to numerous
switching operations. Conventional DPWM methods reduce the power losses and improve efficiency but increase the current total
harmonic distortion (THD). To overcome these weaknesses, this paper proposes a hybrid DPWM switching method combining two
PWM methods: the UP-PWM method and the conventional DPWM method called one-pole clamped PWM method. Since the
proposed DPWM method offers all the advantages of both PWM methods, the optimal performance-with regard to the power losses
and current THD-is obtained. The combination of two PWM methods is investigated by analyzing the power losses and current THD.
Based on the analysis, the process determining the optimal operating condition is introduced. The effectiveness of the proposed
DPWM method is demonstrated through simulations and experiments.
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